The present invention relates to the manufacture and filling of zipper packages on horizontal form fill and seal (HFFS) machines and, in particular to a method for forming such packages two-at-a-time so as to improve production rates and reduce production costs.
It has heretofore been proposed to form and fill packages on HFFS equipment. Such equipment is particularly well suited for the packaging of solid objects such as block or sliced cheese, cold cuts and the like. It has further been proposed to package such items in zippered packaging so as to facilitate the storage and containment of any unused portions of the package after the package is initially opened. Such a method and apparatus is depicted, for example, in U.S. Pat. No. 6,185,907. While such packaging has many apparent benefits a disadvantage is the associated cost which is at least partially due to the production rates and capital expense required to set up the production lines. The problems become complicated where, in addition to a zipper the package is to include a slider to facilitate opening and closing the zipper.
The present invention is a method and apparatus for continuously forming and filling reclosable plastic bags, which include sliders, two at a time. In accordance with the disclosed method a base film of plastic bag making material is horizontally advanced in a longitudinal direction of the film web. The product to be packaged is transversely loaded onto the base film in first and second longitudinally extending lines with the products of the first line aligned with those of the second line. First and second continuous zippers are then applied onto the base film between the lines of product, each of the zippers comprising first and second profiles having mating interlocking portions. Sliders are provided on the zippers between zipper stops formed at bag width intervals. A cover film of plastic bag making material is placed over the base film covering the lines of product and the zippers. The cover film is joined to the base film along longitudinally extending lines disposed on sides of the product opposite to the two zippers. In this connection the cover film may be a separate web in which case the edges of the base film and cover film would be sealed together or the base film and cover film may be formed of a common web with the portions defining the cover folded over the portions defining the base. The first profile of each of the first and second zippers is attached to the base film, the second profile of each of said first and second zippers is attached to the cover film and the base film is attached to the cover film between the first and second zippers. The base film is then sealed to the cover film along transverse seal sections on opposite sides of each row of product running through the zipper stops. The thus formed and filled packages are separated by longitudinally cutting through the base film between the zippers and cutting through the transverse seal sections.